This invention pertains to cigarette production, and more particularly, to temperature conditioning of tobacco to below ambient temperature prior to forming it into a cigarette rod in a cigarette maker.
Cigarette makers are well known in the prior art and a typical unit of this type is sold by Molins Machine Company Ltd. under model number MK9. In the operation of such makers, it is customary for the tobacco filler to be introduced into a feed hopper from which it is fed to a maker region where it is subjected to a pressure differential. In this region, the filler is carried by means of an air flow caused by the pressure differential to a thin, air permeable conveyor or belt. The tobacco is accumulated on the belt and initiates early formation of an accumulation of tobacco which later becomes the maker output cigarette rod. Formation of cigarettes from the rod is carried out by the other customary components of the maker. It is also customary in the trade, to control the temperature and moisture content of the environment in which the aforesaid makers are housed. This is done in order to provide a certain measure of control over the resultant temperature and moisture of the tobacco filler as fed for forming the tobacco rod, and therefore, the resultant desired temperature of the rod produced at the maker. As an example of an attempt to better control rod characteristics, it has been proposed in copending application Ser. No. 111,521, filed Jan. 14, 1980 and assigned to the same assignee hereof, to control the output rod moisture content, for instance, by measuring the moisture content in the maker and adding or subtracting moisture to or from the input stream of tobacco to control moisture content in the rod delivered by the maker.
In such a procedure, a change made in moisture content will affect, to a degree, the firmness of the rod for a given temperature. Therefore, in addition to control over output rod tobacco moisture contents the temperature must be controlled. It would be beneficial and desirable to have a more positive and much higher degree of temperature control of the tobacco filler during transit through the maker to better condition the rod for handling under extremely high speeds in the maker. Such precise control of temperature would enable one to better interpret the readings of the sensing mechanisms of the maker, such as the readings of the firmness levels and the mass of the tobacco as well as the moisture content. Also, for instance, the cutting action of the cigarette rod cutting apparatus may produce fewer rejects due to tobacco dislodged during cutting if rod temperature is reduced by cooling to below ambient temperature.
A further advantage which results from the control of filler temperature by cooling prior to making up the cigarette rod to below ambient temperature is better control of the cigarette characteristics which result after the manufactured cigarettes are placed into a cigarette pack and are passed on into the channels of commerce. The inventor recognized the significance of the full effect of the below-ambient level of temperature at which the filler is held while transiting through the maker in that not only does filler temperature affect the efficacy of the making machine functions, it also affects the final characteristics of the cigarette as a product when it finally equilibrates in residence in the pack. The feel of a cigarette to the hand of a smoker is a very important characteristic affecting the desirability of a particular brand. The resistance to draw of a cigarette as it is smoked must be within desirable limits. The total mass of tobacco content of the rod should also be controlled, in that if total tobacco content varies, several other characteristics of the finished product may vary. All of the above characteristics are affected by the temperature level at which the tobacco filler transits the maker.
It follows, therefore, that if it is desired to produce cigarettes of a given set of specific in-pack characteristics then the entry temperature of the tobacco filler into the rod forming section of the maker must be factored in along with the control of rod firmness, filler moisture content, and Beta gage or total mass readings in order to most accurately forecast the eventual in-pack characteristics of the finished cigarettes.
The cigarette making industry has long recognized and has been dominated by the controlling influence which ambient temperature and moisture conditions have on the characteristics of the tobacco filler content of a machine manufactured cigarette product. Great pains are taken to control the temperature and air humidity of the cigarette making workspace for indirectly controlling filler temperature, etc. However, the inventor recognized that such indirect control of the tobacco temperature was not adequate to the needs and demands of present day advances in cigarette making practices. Cigarette making is now carried out in machinery capable of producing 5000 cigarettes a minute or more. Furthermore, greater advances in speed are being sought to increase the cigarette hourly production rates. As these projected increases in production rates are contemplated, it must be recognized that individual factors such as the particular tobacco filler temperature as it advances to the rod making function become more and more critical to the production of a product of high quality and desired characteristics. Very positive control of the filler conditions such as a reduction in filler temperature must be maintained to allow for greater productivity while assuring predictable, acceptable uniformity of product characteristics and quality. The higher the rate of production desired, the greater the need for more positive control of filler conditions by cooling it to below ambient temperature is needed.
The prior art methods have functioned within the range of ambient conditions of temperature at which a human working environment is comfortably maintained. The moisture content of ambient air in that working environment has been targeted at a particular level to attempt to achieve a degree of control over the filler temperature and moisture content. The level of moisture content in tobacco filler is very sensitive to, and will vary with, ambient moisture content. However filler moisture content will adjust itself based upon the ambient air temperature as well as moisture content. This sensitivity to surroundings is usable to fix moisture content of tobacco, but in accordance with the method of the present invention one may exercise further control by elevating or reducing the temperature of the tobacco.
The moisture content which tobacco assimilates based on ambient conditions is called "equilibration". This means that under given ambient conditions of temperature and moisture, the natural exchange of moisture by the tobacco with the surrounding air will eventually come to a steady-state condition where the exchange of moisture is balance. The term equilibration is readily understood in the trade. To be able to properly target a particular desirable condition of equilibration for cigarettes when eventually at rest in a pack while in the channels of commerce, is a valuable capability. With such a control capability one may positively predetermine and target the exact proportions of moisture filler content needed at a given temperature while making the cigarette rod. Rod firmness, resistance to draw, etc., may also be better provided for when positive control of below ambient temperature of the tobacco filler is exercised during rod formation.
It is to be borne in mind that such characteristics as the above, targeted for and achieved in the pack after equilibration, are not necessarily those exhibited by a cigarette immediately following its manufacture. Thus it becomes extremely important to be able to control the characteristics during processing of tobacco filler in the maker so as to be able to prearrange for and control the characteristics of the newly formed cigarette rod and finished cigarette after reaching, in-pack final equilibration.
The inventor recognized that the above desired condition of equilibration sought to be achieved in the end pack must be provided for in advance through control of the filler characteristics when transiting the making machine. Of prime importance is the need to control the in-process temperature as well as the moisture content, rod firmness, mass measure and other characteristics.
By so controlling the temperature as in the case of the present invention to below ambient temperature and also controlling other above conditions, it is then possible to extrapolate forward and be able to predict pack conditions at eventual equilibration.
Accordingly, it is an object of the present invention to temper tobacco filler by cooling to a desired temperature level prior to or during forming up of a cigarette rod in a making machine to thereby offset heat added by transit through the maker and to idealize speed of production and quality of product and to provide for desired in-pack equilibration levels of moisture content, firmness, feel, and resistance to draw.
It is a further object of the present invention to provide tobacco filler conditioning methods for heating or cooling, i.e.-"temping" the filler prior to entry to, or while within transit through, a maker to counter heat buildup by adhesive heater bars.
It is a further object to provide related apparatus which is adapted to provide such cooling to the filler to better control the speed of making and the physical characteristics of the output rod of tobacco to desired conditions and values, such as for instance the maintenance of a rod temperature which is most suitable for cutting the rod while minimizing the incidence of loose ends.